Issue 1, 2020
It’s been almost a year and a half since the Sea Turtle Conservancy (STC) officially hit the water and kicked off our In-Water Sea Turtle Research Project in Florida. Led by STC Biologist Rick Herren, in collaboration with Dr. Ray Carthy at the University of Florida, the project is focused on determining sea turtle abundance, habitat use, diet, health and movements in the nearshore waters of Florida’s Big Bend. The overall goals are: 1) to better understand the distribution, health, threats and demographic trends of the sea turtles found in the region; and 2) to promote the conservation of sea turtles and their habitats in the Gulf of Mexico.
STC Biologist Rick Herren successfully releases the project’s first satellite tagged green turtle. All work done under FWC MTP #118
The project idea was first conceived more than three years ago, but it wasn’t until fall of 2018 that STC had the funding, permits and equipment to get on the water. When the state and federal permits were finally in place and funding was secured through grants and STC’s Giving Tuesday campaign, we were ready to go thanks to our new, customized research vessel, R/V Lavinia. The boat itself was generously donated by the manufacturer, Carolina Skiff, while the motor, tower, electronics and other equipment were purchased with funds donated by STC Board members and individual donors. The Lavinia’s custom-made tower has a second driving station that aides in the sighting and capture of turtles. It is one of the finest shallow water research vessels on the water – perfect for working with sea turtles in the coastal waters of the Gulf of Mexico. Additional support for the project has come from the University of Florida’s Nature Coast Biological Station, the Florida Cooperative Fish and Wildlife Research Unit and a select group of UF graduate and undergraduate students who volunteer on the project.
STC’s In-Water Project currently has four main objectives. The first is to conduct region-wide surveys of Florida’s Big Bend. This part of Florida is unique for its vast seagrass beds, relatively little shoreline development, and shallow-water habitats that contain foraging green, Kemp’s ridley, loggerhead and hawksbill sea turtles. The goal of these surveys is to determine the distribution and abundance of the different species and size classes in the region. Having completed more than 1,200 km of visual surveys, STC has documented several previously-unreported “hotspots” of sea turtle abundance. These important sites are focal points for ongoing research, which includes the capture, tagging and release of turtles from which important genetic, health, sex and size data are being collected. During visual surveys of the region, STC’s in-water project already has observed over 700 sea turtles, with the majority being juvenile green turtles followed by loggerheads, Kemp’s ridleys and hawksbills. The project’s next objective is to find out why juvenile green turtles aggregate in specific habitats. To answer this question, the team is collecting environmental data in the habitats that are most used by green turtles, including water quality and seagrass nutrient content, and comparing that data with sites infrequently used by green turtles. This work is ongoing, so it’s too early to report findings, but we expect to find a higher abundance of juvenile green turtles in sites which provide shelter from predators and are next to healthy, nutrient rich seagrass beds.
A third objective of the project is to collect data from juvenile green turtles to determine their sex, nesting beach origin, diet and overall health. Blood samples are being collected from captured turtles to determine their sex through hormone analysis and determine their nesting beach origin through genetics. Early data show that over 60% of green turtles in this region have fibropapillomatosis (FP), a tumor-causing disease apparently linked to a herpes virus. This is not too surprising since researchers working in other shallow water lagoons and bays in Florida have found FP rates between 50% and 70%. The most common sites of tumor growth are around the turtles’ soft tissue – on the flippers, neck, eyes, and sometimes internally. Researchers are still unsure how and why green turtles get FP, but the incidence is strongly correlated with the proximity to rivers and land-based sources of pollution. STC and other organizations are working to reduce marine pollution and runoff, while researchers from around the world work to determine how FP is transmitted and to develop effective treatments.
The final objective of the project is to track seasonal movements of green turtles in the region by using satellite transmitters. To date, STC and collaborating UF researchers have deployed six transmitters on juvenile green turtles in the northern and southern Big Bend. Historic and anecdotal data suggests the turtles migrate in the winter to escape colder water temperatures. While it’s too early to tell whether they will stay in the areas they were caught or migrate, STC already is gearing up to deploy additional transmitters to obtain a larger sample size, which should produce more accurate findings about the migratory behavior of this green turtle population.
STC is deeply appreciative of all the support received from various corporate and private donors for this project. Our current project needs include a sub-zero freezer to properly store blood and plasma samples, as well as a project truck dedicated to towing our boat to and from various research sites. We are hopeful that STC’s members will continue to support the program in the coming years as we learn more about this important population and apply that knowledge to effective conservation actions.
Learn more about STC’s In-Water Project.
Sea Turtle Conservancy
